665626397 has 2 divisors, whose sum is σ = 665626398. Its totient is φ = 665626396.

The previous prime is 665626391. The next prime is 665626399. The reversal of 665626397 is 793626566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 658897561 + 6728836 = 25669^2 + 2594^2 .

It is a cyclic number.

It is not a de Polignac number, because 665626397 - 2¹⁴ = 665610013 is a prime.

Together with 665626399, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665626391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332813198 + 332813199.

It is an arithmetic number, because the mean of its divisors is an integer number (332813199).

Almost surely, 2^665626397 is an apocalyptic number.

It is an amenable number.

665626397 is a deficient number, since it is larger than the sum of its proper divisors (1).

665626397 is an equidigital number, since it uses as much as digits as its factorization.

665626397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 50.

The square root of 665626397 is about 25799.7363746221. The cubic root of 665626397 is about 873.1258485631.

The spelling of 665626397 in words is "six hundred sixty-five million, six hundred twenty-six thousand, three hundred ninety-seven".